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Old 05-05-2012, 10:37   #1
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2 meter temp antennea

I have purchased a 2 meter radio to use onboard a boat I will be bringing from Maryland to New Orleans in June. Whats the easiest and least expensive way to have this radio functional for the trip without a permanent instalation. This is my first ham radio, my only experience is with CBs back in the 80,
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Old 05-05-2012, 11:51   #2
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Re: 2 meter temp antennea

1) Ham whip clamped to the stern rail, or bimini framework. Higher is better.

2) Marine VHF whip clamped to the stern rail (SWR won't be great, but it will work)

3) Vertical dipole made from coax (this is definitely the cheapest). Tie one end to the spreader with light line, and the other to a lifeline or something. Run the center feed horizontally for a bit to minimize feedline interaction.

4) Vertical coaxial dipole, made from coax. Just as cheap as (3), and easier to rig. This will take some tuning for best performance. Strip off 1/4 wave of outer insulator, and work the shield braid back down the coax. I would tape over the exposed shield -- this will protect the bare wires from corrosion, at least for a little while.
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Old 06-05-2012, 18:19   #3
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I don't have the details handy, but google J Pole...easy to make and haul aloft. Should be plenty of info online.

K4RCG Bob
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Old 06-05-2012, 19:36   #4
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Re: 2 meter temp antennea

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Originally Posted by Bob on OTTER View Post
I don't have the details handy, but google J Pole...easy to make and haul aloft. Should be plenty of info online.

K4RCG Bob
Excellent suggestion. I've seen them made with 300 Ohm T.V. twinlead (all our TV antennas used to be hooked up with this stuff, before everyone switched to coax). Here's a link to a twinlead J-Pole: The Twinlead J-Pole Antenna
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Old 06-05-2012, 19:59   #5
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Re: 2 meter temp antennea

John, just curious, what's on 2M? I'm a HAM tech, taking general this month, and wondering if you have anything specific in mind or just trying for some contacts.

Chase
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Old 06-05-2012, 21:16   #6
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Re: 2 meter temp antennea

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Originally Posted by Paul Elliott View Post
Excellent suggestion. I've seen them made with 300 Ohm T.V. twinlead (all our TV antennas used to be hooked up with this stuff, before everyone switched to coax). Here's a link to a twinlead J-Pole: The Twinlead J-Pole Antenna
Thanks for that, Paul! Seems like something we should all have rolled up somewhere, slightly modified for marine VHF frequencies... the perfect emergency antenna.

And I think I'll try one for 2 metres too!

73 de Jim N9GFT/VK4GFT
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Old 06-05-2012, 21:32   #7
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Quote:
Originally Posted by Jim Cate

Thanks for that, Paul! Seems like something we should all have rolled up somewhere, slightly modified for marine VHF frequencies... the perfect emergency antenna.

And I think I'll try one for 2 metres too!

73 de Jim N9GFT/VK4GFT
On 20m now. Dipole hauled up on a spare halyard! working DX from OTTER with 50w from an old Kenwood TS50. 73 de Bob K4RCG
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Old 07-05-2012, 02:16   #8
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Re: 2 meter temp antennea

I would definitely not go for a J-Pole.

They are difficult to tune and very easily detune with any metal objets in the neighbourhood of the antenna base.

I would go for the "coaxial 1/2 dipole" solution, either as a temporary wire antenna or put into a plastic tube enclosure. The latter will also require some pruning and tuning since the enclosure will have an "electric lengthening effect" hence you will have to shorten the dipole.

In an enclosure it would become a reliable "permanent temporary" antenna....

Good luck,

Jan
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Old 07-05-2012, 13:44   #9
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Found a 2 meter ham whip and a mirror mount that I could secure to the Bimini. Would there be any problems with that
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Old 08-05-2012, 06:20   #10
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Re: 2 meter temp antennea

Hi John,

no that would definitely work if it is a dedicated 2m whip antenna, depending if it needs a ground plane like the car metal or not.

In general it would be far better to place it at the masttop since it will have a better radiation pattern there.
If I model a vertical dipole for 2 m at low height above seawater, it shoots a bit upward starting at 12 takeoff angle.
But then the same goes for marine VHF antennas, I have a dedicated AIS RX antenna on the pullpit at 2.2m base height so it must show the same slightly suboptimal vertical radiation pattern.

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